The present invention relates to producing printed-circuit boards with transmission lines utilizing inductance.
Printed circuit boards are widely utilized in the electronics industry. They typically consist of multilayer substrates having copper traces and plated-through holes to connect electronic components mounted on the circuit board.
Producing a plated-through hole (xe2x80x9cviaxe2x80x9d) on a multilayer printed-circuit board is typically performed by boring through the typically copper-clad printed-circuit board at locations at which a via is desired. Then, using typically a galvanic process, copper is deposited on the inner wall of the bored hole forming a conductor that connects a top surface of the printed-circuit board to the bottom surface of the printed-circuit board. Along with plating the bore of the via hole, the copper also typically covers the top and bottom surfaces of the printed-circuit board to form conductive surfaces thereon. Subsequently, the copper surfaces are etched as desired to form circuitry. This circuitry may form a transmission line that connects two or more electronic devices together.
Multi-layer printed-circuit boards, in addition to the top and bottom conductive surfaces, typically include middle layers that are also conductive. These middle layers may be used for a variety of purposes including distributing power and ground connections to the variety of devices that may be assembled on the printed-circuit board. In some cases, it may be desired that a via connect the top and bottom connective surfaces of the printed-circuit board but remain isolated from ore or more of the middle layers that may be utilized as ground and power planes.
However, while there may not be a direct electrical connection between the isolated via and the ground and power planes, there is nevertheless a capacitance effect which couples signals that may be conducted by the via to the ground and power planes. This capacitance effect is exacerbated as the frequency of the signals which may be conducted by the via increase. At frequencies exceeding a gigahertz range, this effect may become significant and serve to limit the distance with which signals may be coupled on the printed-circuit board or through connectors to other circuit boards.
The current trend in the industry is to use higher frequency signals, thus there is a need in the industry for an improved method of propagating high frequency signals utilizing printed-circuit boards.